On the right track

by K.N.C. | London

DATA visualisation enables us to learn from information. Jo Wood, a professor of visual analytics at City University London, found a terrific way to depict a vast amount of data in a neatly accessible way—plotting all the bicycle journeys taken by London's municipal bike-sharing service in the first year of operation in 2010-11; some five million trips. The result is the magnificent video-graphic below.

How now, such data? The bicycles do not have wireless GPS modules attached; they're not "spy-cycles." Rather, the system records the time and location when each bike is taken from and returned to a docking station. Based on this, Mr Wood was able to divine the probable route. The information is released publicly by Transport for London (TfL), though Mr Wood has access to even more data for other projects he is working on with TfL.

In the video infographic, one sees small blue wisps (representing bike trips) emerge like tiny water hydra swimming randomly under a microscope's lens. As more data comes, patterns start to form, depicted by bolder, white lines. Finally, just the most common routes are shown. The rectangle on the upper left, for instance, are cyclists at Hyde Park.

"The video-graphic shows that by changing aspects of the visual design, we can bring out the structure in movement patterns that might otherwise be hidden by the chaos of millions of journeys," explains Mr Wood. How this was achieved is described in a paper by Mr Wood and his colleagues Aidan Slingsby and Jason Dykes.

Visualising the data is critical for understanding things like where to build docking stations and how many bikes to stock where, and at what time of day. The interests of commuters going to work from transport hubs like Waterloo and King's Cross St Pancras are different than that of punters enjoying a weekend pedal. The data also track the number of users from outside London, as well as differences between men and women in terms of travel speeds.

In the past this sort of information was only available with self-reported surveys or counters at traffic junctions; all imperfect measures. Now harnessing the actual usage information is feasible, for those with the imagination, skill and tools to bring the data to life. /economist